All patients developing non-A, non-B hepatitis following open heart surgery will be followed with serial studies of ALT to determine the incidence of chronic liver disease and to compare this incidence with those having type B hepatitis. Liver biopsy will be obtained when the ALT is elevated for more than 6 months and then again at one and three years. Biopsy material will be obtained for fluorescent and EM studies, as well as light microscopy with multiple stains.